"A Potential New Drug for Depression," an active SBIR Phase IIa award. The requested funds will allow additional characterization studies of three newly discovered mixed vasopressin 1a/1b antagonists, studies that were not part of the original application. These experiments will accelerate preclinical development of the novel mixed antagonists by facilitating identification of clinical candidates within this group of compounds. Arginine Vasopressin (AVP) antagonists represent a novel therapeutic class for the treatment of depression. The potential utility of these compounds has emerged from observations in depressed individuals, findings in animal models, and an understanding of changes in hypothalamic-pituitary-adrenal (HPA) axis regulation under chronic stress. The active Phase IIa award has two objectives. One is advancing the development of our lead clinical candidate, SRX246-HCl, through a Phase I Clinical Trial. SRX246 is a novel vasopressin 1a (V1a) receptor antagonist that had shown efficacy in preclinical animal models of depression and anxiety, good plasma bioavailability and CNS penetration following oral administration, a strong safety profile, and high affinity and selectivity for the target receptor, The development of this compound to date has been supported by SBIR Phase I, Phase II, and Phase IIa grants, the National Toxicology Evaluation program, a RAID grant, and Series A and Series B private sector investments. All IND-enabling toxicology and safety pharmacology has been completed and an IND application is now under review at the FDA. Assuming approval, a Phase I Clinical Trial to establish safety and tolerability in humans will start in June or July, 2009. The second objective is continued development of back-up compounds, including additional V1a antagonists and mixed AVP 1a/1b antagonists. The Revision Application seeks additional support for preclinical studies that will accelerate clinical candidate identification among newly discovered back-up compounds that are mixed V1a/V1b antagonists. Achieving these goals will enhance commercialization opportunities for Azevan by significantly advancing the likelihood of a partnership with a major pharmaceutical house and/or attracting additional private sector investment. PUBLIC HEALTH RELEVANCE: The public health need for new pharmaceutical treatments for depression is well documented. Depression affects some 20 million Americans each year and carries a conservatively estimated annual total economic burden of $125 billion. Existing drugs for depression are not uniformly effective and frequently have undesirable side effects. These limitations demonstrate that a new treatment approach through vasopressin receptor antagonism in the brain may offer significant opportunities for improved outcomes with substantial societal benefit.